Adsorption of hexavalent chromium in aqueous solution on activated carbon prepared from apple peels

In the present study, activated carbon prepared from apple peels (ACAP) was used to remove chromium (VI) from aqueous solution. The characterization of this ACAP has been performed using different analytical techniques such as FTIR and SEM. The adsorption parameters studied were: pH [2- 7], adsorbent dose [0.025-0.15 g/50 mL], initial Cr(VI) concentration [10-50 mg/L] and temperature [10-40 degrees C]. Maximum Cr(VI) adsorption of 36.01 mg/g was achieved using Cr(VI) concentration of 50 mg/L, pH of 2, adsorbent dose of 0.05 g/50 mL, contact time of 4 hand temperature of 28 degrees C. This ACAP gave a Cr(VI) adsorption capacity better than a commercial activated carbon. The experimental data fitted well to Freundlich isotherm (R-2 = 0.99) and kinetics followed the pseudo-second order model. Thermodynamic parameters, Delta G < 0, Delta H degrees = 1.99 (Kcal/mol) and Delta S degrees = 0.0079 (Kcal/K mol) indicate that the adsorption process is spontaneous and endothermic.